Application of Vacuum Degassing Furnace in Electric Steelmaking

0 vacuum degassing (VD) treatment process, can reduce the molten steel in the furnace Steel Co., Ltd. VD treatment of steel are: hard-wire steel (72A, 82B), the combined steel (40Cr, 20CrMnTi, 20CrMnMo, 35CrMo), spring steel (60Si2Mn), bearing steel (Gl5) and cold heading steel (ML42CrMo). Now make a brief introduction to communicate with your peers.

1 System Overview 1.1 The degassing system is made up of components, and the supporting boilers are supplied by Standard-kesseidersburg. This set of devices is more advanced in similar domestic products.

The degassing system is used as the main equipment of the VD furnace and consists of two vacuum tanks (can diameter 5800, tank height 5450), vacuum lid system, vacuum funnel, temperature sampling system, duplex double wire feeding system, argon blowing system and Mobile cart and other components.

1.2 Computer system 1.2.1 The vacuum degassing furnace is composed of two levels of basic automation and process control computer control (see below).

Industrial Ethernet PR0FBUS control system overall structure diagram The first-level computer system uses electrical, instrumentation, computer control trinity of the basic automation level, composed of PLC (Siemens S7-400 series) and host computer (MMI).

The main module is 6ES7 communication module 6GK7 series.

2 Control Principles and Basic Processes The related control parameters are set through the MMI screen.

Relevant data are sent to VD furnaces, boilers and PLCs of wire feeding machines through SINECH1 bus to control the relevant electrical operation. At the same time, a single instrument detection signal is collected at the same time as the basis for automatic control.

The VD furnace master receives the processing tasks sent from the previous process. In addition, it also includes the motor control center (MCC), the boiler control system, the wire feeder, the cover control system, and the on-site detection element. Man-machine interface MMI uses INTOUCH graphical interface software programming.

The secondary computer system uses a process control station and is connected to the electric furnace computer Ethernet. Process control station using multi-processor host, operating system is WindowsNT, network protocol is TCP/IPSINECH1, basic software: industrial ORACLE, database C/C++ 1.2.2 main function basic automation level (a): furnace cover operation control Feeding control; regenerator pump control; degassing process screen display; active bending station switch; bottom-blown mixing control; ferroalloy feeding control; water treatment control; man-machine dialogue interface; dust control system; cooling water system Control; steam injection control; equipment abnormal alarm and interlock; molten steel splash monitoring; alarm and event printing.

Process control level (2): calculation of energy balance mathematical model; calculation of mathematical model of molten steel temperature, composition and processing time; control of operation process, operation guide and accident records; data detection of production process and storage of historical data; And processing; communication with the electric furnace, continuous casting, laboratory control system; production report printing.

1.3 On-site inspection instrumentation In order to ensure the measurement accuracy, on-site inspection instruments basically adopt imported parts with better quality, such as: and related data, start data processing and refining preparation. The vacuum furnace has 2 degassing tanks and 1 vacuum cover car parking place. The vacuum cover car is parked in the middle of 2 vacuum tanks. After the ladle is in place, an argon gas pipe is manually connected, and the vacuum cover truck is put in place and the vacuum cover is lowered. According to the evacuation speed and processing steps required for processing the molten steel, the steam ejector is turned on for vacuum processing. In the vacuum state, the bottom of the ladle is blown with argon to measure the temperature. The alloy can be added to the vacuum funnel on the vacuum cover to fine-tune the composition of the molten steel. After vacuum treatment, the vacuum is broken, the vacuum lid rises back to the rest position, or it moves to another vacuum position.

In the open state of the ladle, continue blowing argon and soft stirring and feed the wire. After the treatment is completed, the final temperature sampling is performed. At this time, vacuum processing of the next packet of molten steel can be performed in another tank position. In the molten steel process, the gas content can be quickly determined by means of constant hydrogen and oxygen meters.

Vacuum processing can choose automatic mode, manual mode and standard mode. When the automatic mode is selected, E5a, E4 and £ are pumped according to the ambient atmospheric pressure (about lOlkPa) and when the vacuum degree reaches 10kPa, the standard mode is selected, the system automatically stops the E5a, E4a pump, and the E5 pump is turned on. The E4 pump remains unchanged. When E3, E2, E1 pumps are selected in manual mode respectively, the vacuum pump system generally operates in the standard mode, gradually open the check valve and the turbid water valve, according to the ambient atmospheric pressure, 3 vacuum degassing operation points and precautions End of VD treatment of each furnace After that, inspect the heat insulation layer at the center of the lower surface of the large can lid. If it falls off, handle it properly.

When evacuating, the flow of Ar gas must not exceed 400 NL/min and the pressure should not exceed. 5MPa (gauge pressure), to avoid the molten steel stick to the small stove lid and the top edge of the ladle, so as not to lift the lid or pull off the ladle liner.

Development of 55CrSi Wire Rods for Automobile Suspension Springs with a Fire-Based Process Ye Jiansong 1 Yu Guosong 1 Wu Xiaoliang 1 Wang Wengui 2 Zhou Yin 3 (Hangzhou Iron and Steel Group Co., Hangzhou 310022 1. Technology Center; 2 Changxing Electric Furnace Co., Ltd.; 3. High-speed wire rod company) 55CrSi wire rod situation. The test results of the chemical composition, surface quality, metallurgical structure, inclusion content and mechanical properties of the wire rod showed that the wire rod surface quality, decarburization layer, mechanical properties and other indicators reached the advanced level of similar domestic products. It can meet the requirements of different reed spring processes, and the fatigue life of the spring can meet the national standards of the automobile suspension spring.

0 Chicoi Automobile Suspension Spring 55CrSi high-quality wire rod is a difficult and high value-added product in the wire industry. 5. It is understood that only a few steel mills in the country currently produce such steels, such as Baosteel, Hangzhou Iron and Steel, and Wuhan Iron and Steel. Steel mills generally adopt the production technology of large-scale converter smelting, die casting, blanking, high-line rolling or electric furnace, die-casting, and blank-high-line rolling. Hangzhou Iron & Steel successfully developed electric furnace smelting in November 2003. Casting - high-line rolling a new process of fire wood production. The difficulty in the production of the new process lies in the effective control of the residual alloying elements, nitrogen content and inclusion level in the smelting of the electric furnace and the guarantee of the quality of the continuous casting slab. The advantage is that the continuous casting billet is turned into a raw material, the production cycle is shortened, the comprehensive finished product rate is increased, and the production cost is reduced. . In the following, the 55CrS wire rod found that the overflow should be promptly broken, and at the same time, the flow of Ar gas can be properly adjusted to press the residue.

4) During the high-vacuum holding stage (67Pa), the At flow rate can be adjusted to increase the exposed surface of the molten steel to accelerate degassing. At the same time, close attention must be paid to the temperature change at the bottom of the tank.

5) Under the condition of vacuum, if the water level of the hot water tank exceeds 100% and cannot fall below 100% within 5 seconds, vacuum should be broken immediately, and then the turbid water should be stopped immediately after all steam valves are closed to prevent the water level from being too high. High pressure broken hot water tank.

6) After each furnace VD treatment is completed, after the tank cover truck is opened, it is necessary to promptly check the situation of the ladle trunnion and the ladle support base in the tank. If there is molten steel sticking, it is necessary to immediately command the vehicle to try and hang the ladle; if there is cold steel sticking , must be cleared before hanging.

Production process, physical quality and mechanical performance are introduced.

1 Production process In the production of the 55CrSi wire rod of Hangzhou Steel, relying on the advanced smelting, rolling equipment and reasonable process to carry out clean smelting and less defects on the surface of the wire rod control rolling: on the one hand to control the quality of hot metal, scrap steel and into the furnace Control the residual element content in molten steel; on the other hand, adopt appropriate deoxidation and secondary refining processes to control the contents of 0, N, A1, S, P, and H in the molten steel; in addition, a reasonable continuous casting process is used to control the connection. Billet quality. In order to obtain the desired surface quality and performance organization of the wire rod, the surface of the continuous casting blank is subjected to magnetic particle inspection and grinding prior to rolling; the appropriate heating, rolling, and controlled cooling processes are selected for rolling to ensure that the decarburized layer of the wire rod is shallow. With fewer defects, high dimensional accuracy, and reasonable organization, the effect of 4VD treatment is that the molten steel in the electric furnace can be reduced to 2X10-6 or less and 80XUT6 or less after vacuum degassing, and the yield per ton of steel can be significantly increased.

Practice has proved that the investment of the vacuum degassing furnace is very favorable for adjusting the product structure of the steel structure of Hangzhou Iron & Steel and further improving the product quality.

-01 Reviewer: Lin Dekang Editor: Wu Peiliang

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